Description: The virtual memory necessary to run your Exchange server is
fragmented in such a way that normal operation may begin to fail. It is
highly recommended that you restart all Exchange services to correct this issue.

The passive node maintains a stub store.exe process. If the passive node at one time hosted the virtual server and was not restarted after it released ownership of the virtual server, the memory in the store process already contains fragmentation.

To clear fragmentation, restart the current passive node, and then fail cluster resources to the newly restarted node. Additionally, restart the previously active node in case an unexpected failover was to occur.